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The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the weekly PCM newsletter. Or join the discussion on LinkedIn.

Two Entropy advisors, Dr. Mohammed Farid and Lucas B. Hyman, are pleased to take your questions about PCMs and thermal energy storage. Send your questions to bwelter@puretemp.com. We'll select the best and post the answers here each week.

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Research roundup: Rubber sealing materials; pork fat as novel PCM; thermal inertia of buildings; more

Ben Welter - Wednesday, September 20, 2017

Feasibility of Using Microencapsulated Phase Change Materials as Filler for Improving Low Temperature Performance of Rubber Sealing Materials [Soft Matter]

Evaluation of the nanofluid and nano-PCM based photovoltaic thermal (PVT) system: An experimental study [Energy Conversion and Management]

Investigation of pork fat as potential novel phase change material for passive cooling applications in photovoltaics [Journal of Cleaner Production]

Superwetting polypropylene aerogel supported form-stable phase change materials with extremely high organics loading and enhanced thermal conductivity [Solar Energy Materials and Solar Cells]

Polyethylene glycol-enwrapped silicon carbide nanowires network/expanded vermiculite composite phase change materials: Form-stabilization, thermal energy storage behavior and thermal conductivity enhancement [Solar Energy Materials and Solar Cells]

Solar desalination using solar still enhanced by external solar collector and PCM [Applied Thermal Engineering]

Using Thermal Inertia of Buildings with Phase Change Material for Demand Response [Energy Procedia]

Preparation of microencapsulated phase change materials (MEPCM) for thermal energy storage [Energy Procedia]

Study of thermal conductive enhancement mechanism and selection criteria of carbon-additive for composite phase change materials [International Journal of Heat and Mass Transfer]

German researchers roll out PCM warming mats for greenhouse plants

Ben Welter - Tuesday, September 19, 2017

Researchers at the University of Zwickau's Institute for Textile and Leather Technologies are developing a latent heat storage mat that uses phase change material to increase plant root temperatures in cold seasons. 

Dr. Silke HessburgThe passive system, designed for use in greenhouses, requires no additional energy supply. Dr. Silke Hessberg, who is directing the research, says root climate control promotes plant growth efficiently.

"There are already various heating systems on the market, such as underfloor heating systems, hot water systems or electric and gas heaters," she says. "These are always cost-intensive heating systems, since energy must be actively supplied."

The Thuringian Institute of Textile and Plastics Research (TITK) is supporting the two-year project. TITK's Martin Geissenhöner identifies the PCM as paraffin. 

"We have different melting points. For the root project we use melting points between 5 and 42° C, specially 17° C," he says. "The PCM is encapsulated in a network polymer. It's like a sponge structure."

Research associate Nancy Schrader says the mats are placed on the soil surface. Work on the project began in May 2015 and is expected to conclude in December. 

PCM briefing: Solar-powered micro cold rooms; Axiom Exergy's jazz connection

Ben Welter - Wednesday, September 13, 2017

• The German company Covestro is providing technology for use in solar-powered micro cold rooms in India. The cold rooms employ phase change material to keep produce cool until it can be transported from farm to market. Eight hundred units will be built in the Indian state of Telangana over the next two years. 

• In an interview with the San Jose Mercury News, Anthony Diamond talks about the musical connection he shares with Axiom Exergy co-founder Amrit Robbins. They met as undergrads at Stanford University. "I play saxophone, he’s actually a trumpet player," Diamond said. "He was like, the best jazz trumpet player on campus. So whenever I had a gig, I would call him, and vice-versa. We had an opportunity to collaborate a lot within that context. I knew that I worked really well with him and we were a really great team."

• Heat battery maker Sunamp Ltd. is one of 15 European scaleups selected to give presentations in California next week at Startup Europe Comes to Silicon Valley

Pelican BioThermal has opened a service center in Puerto Rico. The center will serve as a depot for the company’s Credo on Demand rental program and enable customers to receive and return reusable temperature controlled packaging systems.

Facebook has announced that its cloud campus in Odense, Denmark, will be connected to a neighborhood district heating system. The company expects the system will warm 6,900 homes.

Evelyn Wang, director of MIT’s Device Research Laboratory and an internationally recognized leader in phase change heat transfer on nanostructure surfaces, has been named associate department head of operations in the school's Department of Mechanical Engineering.  

Long-Qing Chen, professor of engineering science, mechanics and mathematics at Penn State University, has been awarded a Humboldt Research Award by the Alexander von Humboldt Foundation of Germany. Chen will work with Jürgen Rödel, professor of materials science and engineering at the Technische Universität Darmstadt, on areas of mutual interest, including multiferroic thin films and phase change materials.

MIT researchers are taking a look at 3,000-year-old technology that could help reduce the use of fossil fuels. Under the proposal, electric resistance heaters would convert excess electricity into heat. The heat would be stored in a large mass of firebricks, which can retain heat for long periods if they are enclosed in an insulated casing. The heat could be used directly for industrial processes, or it could feed generators that convert it back to electricity when the power is needed.  

Research roundup: Carbonized rice; erythritol-xylitol; integrated double skin façade; paraffin-based TES system; more

Ben Welter - Wednesday, August 30, 2017

Form stable composite phase change materials from palmitic-lauric acid eutectic mixture and carbonized abandoned rice: preparation, characterization, and thermal conductivity enhancement [Energy and Buildings]

Mitigation against Crude Oil Wax Solidification using TES Fin [Chemical Engineering Research and Design]

Heat transfer analysis of an integrated double skin façade and phase change material blind system [Building and Environment]

Experimental Phase Diagram Study of the Binary Polyols System Erythritol-Xylitol [Solar Energy Materials and Solar Cells]

Study of Various Aspects of Phase Change Material During Solidification and Melting: A Review [pdf] [International Journal of Scientific Research in Science and Technology]

Development in Paraffin Based Thermal Storage System Through Shell and Tubes Heat Exchanger With Vertical Fins [ASME 2017 11th International Conference on Energy Sustainability]

Patent application: Thermal energy battery with enhanced heat exchange capability

Ben Welter - Friday, July 28, 2017

U.S. patent application 20170205152 (applicant Promethean Power Systems Inc., Somerville, Mass.):

Thermal storage battery patent drawing"This invention provides a thermal energy battery having an insulated tank contains a multitude of densely packed plastic tubes filled with a phase-change material (PCM, such as ice) that changes from solid to liquid and vice-versa. Energy is stored when the PCM transitions from liquid to solid form, and released when the PCM transitions back from solid to liquid form. The tubes are arranged vertically, span the height of a well-insulated tank, and are immersed in heat transfer fluid (HTF) contained within the tank. The HTF is an aqueous solution with a freezing point temperature below the freezing point temperature of the chosen PCM. The HTF remains in liquid form at all times during the operation of the battery. Diffusers located allow the HTF to be extracted uniformly from the tank, pumped and cooled by a liquid chiller situated outside the tank and then and inserted back into the tank."

http://www.freepatentsonline.com/20170205152.pdf

Patent application: Enclosure temperature control system

Ben Welter - Thursday, January 19, 2017

U.S. patent application 20170013789 (applicant Sustainable Energy & Agriculture Technology, Sahuarita, Ariz.):

SEAT patent application drawing"An enclosure temperature control system utilizes a renewable power source and a thermal sink to reduce the overall power requirements from a power grid. A renewable power source, such as a solar panel may provide power that drives the components required to maintain the greenhouse temperature within upper and lower limits, including a HVAC system and/or a heat transfer system coupled with a thermal sink. The thermal sink includes a phase change material that releases heat when it solidifies and this heat can be used to heat the greenhouse. Likewise, the phase change material absorbs heat during the day to reduce the temperature within the greenhouse. A heat transfer system may be coupled with the phase change material and a solid conductor component within the tank of a phase change material may increase thermal transfer rate."

http://www.freepatentsonline.com/20170013789.pdf

Research roundup: Battery thermal management; plastic greenhouse thermal modeling; cementitious composites; more

Ben Welter - Wednesday, December 21, 2016

Investigation of phase change material based battery thermal management at cold temperature using lattice Boltzmann method [Energy Conversion and Management]

A study on thermal calculation method for a plastic greenhouse with solar energy storage and heating [Solar Energy]

Assessing the feasibility of integrating form-stable phase change material composites with cementitious composites and prevention of PCM leakage [Materials Letters]

Expanded graphite/disodium hydrogen phosphate/sodium acetate trihydrate stabilized composite phase change material for heat storage [pdf] [Journal of Thermal Science and Technology]

Coupling of solar reflective cool roofing solutions with sub-surface phase change materials (PCM) to avoid condensation and biological growth [Environmental Science and Sustainable Development]

Experimental Study on Thermal Performance Improvement of Envelop Integrated with Phase Change Material in Air-conditioned Room [International High Performance Buildings Conference]

U.S. patent: Rootzone heating for energy conservation using latent heat storage

Ben Welter - Monday, December 12, 2016

U.S. patent 9,510,515 (inventor Dr. William R. Sutterlin, Hoover, Ala; assignee Entropy Solutions LLC, Plymouth, Minn.):

U.S. patent image of root zone with micro PCMs"A plant pot or a plant container comprising: a phase change material (PCM) or a composition comprising a PCM, wherein the plant pot or plant container is formed from or has as part of its structure or has as a structural component comprising the PCM or composition comprising the PCM, and a sufficient amount of PCM is provided in or part of the plant pot or plant container to maintain a root zone environment having a consistent temperature environment or optimal temperature environment for a plant's root system growth or maintenance, and wherein the PCM or the composition comprising the PCM: (a) is positioned in as part of the plant pot or plant container to be approximate to, close to, in contact with, or substantially in contact with, the plant root system or a soil, or (b) is present as part of or as a structural component of the plant pot or plant container, in an amount sufficient to maintain a root zone environment having a consistent temperature environment or optimal temperature environment for the plant's root system growth or maintenance."

http://www.freepatentsonline.com/9510515.html

New wave of greenhouses use PCM to regulate temperature

Ben Welter - Monday, December 12, 2016

Traditional greenhouses are not all that green. Poor insulation and inefficient heating and cooling systems boost energy consumption and operating costs.

Colorado-based Ceres Greenhouse Solutions is among the growing number of companies offering commercial growers and backyard gardeners a better way. Ceres has designed and built hundreds of energy-efficient, year-round greenhouses since 2011. Key features include the use of free solar energy for both heating and cooling, improved insulation and phase change materials. Ceres says it is the first greenhouse company to integrate PCMs into its residential and commercial installations.

"We specialize in passive solar design — maximizing the use of solar energy for year-round heating," says Lindsey Schiller, director of marketing and business development. "These [greenhouses] use a combination of insulation and strategic placement of glazing (glass or plastics). The result is a more insulated and energy-efficient greenhouse capable of growing year-round in harsh climates with very little energy use. We also are well known for using a ground-to-air-heat exchanger we call the GAHTTM system, as well as integrating other sustainable / energy-efficient / renewable heating cooling systems."

Ceres greenhouse wall with PCM facingCeres uses film panels filled with phase change material to provide passive temperature control. The panels, sized to fit in a typical stud bay, help even out day-night temperature swings and reduce the need for active heating and cooling. The peak melting point of the PCM varies by climate.

"We usually recommend 60 F for cold-climate greenhouses with cold-tolerant crops where heating is needed, 80 F for hot-climate areas with heat-tolerant crops where cooling is the primary focus and 70 where both is desired," Schiller says. The panels are typically installed on the inner face of the north wall, as shown here.

The company originally used Phase Change Energy Solutions' BioPCM but recently switched to Insolcorp's Infinite R, a salt hydrate. Ceres sells the PCM for $3.50 a square foot. 

“One of the major things we have to think about is the durability of the packaging, particularly since it is exposed to direct light,” says Schiller. “We were concerned about the lifetime of BioPCM and switched to make sure we had a durable product that will hold up in a greenhouse environment.”

Another method for passive temperature regulation: fish tanks. Ceres recently announced a partnership with Colorado Aquaponics, a company that specializes in pre-fabricated aquaponic greenhouses. Ceres now offers kits that pair space-efficient aquaponic systems with highly efficient year-round greenhouses. Can PCMs play a role in these hybrid greenhouses?

"Yes," says Schiller, describing the technologies as complementary. "Greenhouses usually need several strategies to help control temperatures … not just one."

Research roundup: Polyethylene glycol/hydroxyapatite composite; root zone heating; lime plasters; more

Ben Welter - Tuesday, November 29, 2016

A polyethylene glycol/hydroxyapatite composite phase change material for thermal energy storage [Applied Thermal Engineering]

Phase diagrams, eutectic mass ratios and thermal energy storage properties of multiple fatty acid eutectics as novel solid-liquid phase change materials for storage and retrieval of thermal energy [Applied Thermal Engineering]

Analysis of the technical, environmental and economic potential of phase change materials (PCM) for root zone heating in Mediterranean greenhouses [Renewable Energy]

Effect of inclination angle on the melting process of phase change material [Case Studies in Thermal Engineering]

Densities of Selected Phase Change Materials in Liquid State [Chemical Data Collections]

Hygrothermal performance improvement of the Korean wood frame walls using macro-packed phase change materials [Applied Thermal Engineering]

Reinforcing and shape stabilizing of phase-change material via graphene oxide aerogel [Carbon]

PCM-enhanced Lime Plasters for Vernacular and Contemporary Architecture [Energy Procedia]

Characterisation and Enhancement of Phase Change Slurries [Energy Procedia]

Packed-bed Thermal Energy Storage Analysis: Quartzite and Palm-Oil Performance [Energy Procedia]

Thermal properties and reliability of eutectic mixture of stearic acid-acetamide as phase change material for latent heat storage [Journal of Chemical Thermodynamics]

Application of material assessment methodology in latent heat thermal energy storage for waste heat recovery [Applied Energy]